BS PD CEN TR 16797-1-2015 Construction products Assessment of release of dangerous substances Guidance on the statistical assessment of declared values Principles and rul.pdf

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1、BSI Standards Publication PD CEN/TR 16797-1:2015 Construction products: Assessment of release of dangerous substances Guidance on the statistical assessment of declared values Part 1: Principles and rules of applicationPD CEN/TR 16797-1:2015 PUBLISHED DOCUMENT National foreword This Published Docume

2、nt is the UK implementation of CEN/TR 16797-1:2015. The UK participation in its preparation was entrusted to Technical Committee B/557, Construction products - Assessment of dangerous substances. A list of organizations represented on this committee can be obtained on request to its secretary. This

3、publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2015. Published by BSI Standards Limited 2015 ISBN 978 0 580 85717 1 ICS 03.120.20; 91.100.01 Compliance with a British Standard ca

4、nnot confer immunity from legal obligations. This Published Document was published under the authority of the Standards Policy and Strategy Committee on 30 September 2015. Amendments issued since publication Date Text affectedPD CEN/TR 16797-1:2015TECHNICAL REPORT RAPPORT TECHNIQUE TECHNISCHER BERIC

5、HT CEN/TR 16797-1 August 2015 ICS 03.120.20; 91.100.01 English Version Construction products: Assessment of release of dangerous substances - Guidance on the statistical assessment of declared values - Part 1: Principles and rules of application Produits de construction - Evaluation de lmission de s

6、ubstances dangereuses Guide pour lvaluation de la performance et la vrification de sa constance - Partie 1 : Principes et rgles dapplication This Technical Report was approved by CEN on 16 January 2015. It has been drawn up by the Technical Committee CEN/TC 351. CEN members are the national standard

7、s bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Sloven

8、ia, Spain, Sweden, Switzerland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels 2015 CEN All rights of exploitation in any form and by any means reserved w

9、orldwide for CEN national Members. Ref. No. CEN/TR 16797-1:2015 EPD CEN/TR 16797-1:2015 CEN/TR 16797-1:2015 (E) 2 Contents Page European foreword .3 Introduction .4 1 Scope 5 2 Declared values5 3 Other principles .6 4 Uncertainty .8 5 Rules of application .8 5.1 Introduction to the rules of applicat

10、ion .8 5.2 Rule of application based on assessment by variables . 11 5.2.1 Principles of assessment by variables . 11 5.2.2 Type-testing . 14 5.2.3 Further-testing 14 5.2.4 Use of existing data and sharing data 16 5.2.5 Outliers 17 5.2.6 No-further-testing (NFT) . 17 5.3 Rule of application for prod

11、ucts where the test values are significantly below the declared value (gamma rule) . 18 5.4 Rule of application based on assessment by attributes 20 5.4.1 Where assessment by attributes should be selected . 20 5.4.2 Type-testing . 21 5.4.3 Further-testing 21 5.4.4 Use of existing data and sharing da

12、ta 22 5.4.5 Outliers 22 5.4.6 No-further-testing . 22 Bibliography . 24 PD CEN/TR 16797-1:2015 CEN/TR 16797-1:2015 (E) 3 European foreword This document (CEN/TR 16797-1:2015) has been prepared by Technical Committee CEN/TC 351 “Construction products: Assessment of release of dangerous substances”, t

13、he secretariat of which is held by NEN. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. CEN/TR 16797, Construction products: Assessmen

14、t of release of dangerous substances Guidance on the statistical assessment of declared values, comprises the following two parts: Part 1: Principles and rules of application the present document; Part 2: Technical and statistical background. PD CEN/TR 16797-1:2015 CEN/TR 16797-1:2015 (E) 4 Introduc

15、tion The present document provides a brief introduction as to how to declare performance for the potential release, emission and/or content of dangerous substances from or in construction products and gives the principles which underpin the acceptance criteria of test results in relation to a declar

16、ed value. The main rules of application are introduced, all of which satisfy the given principles. CEN/TR 16797-2 1 provides more detailed background and technical explanation together with examples and the statistical justification for the rules of application. The definitions and abbreviations lis

17、ted in CEN/TR 16797-2:2015, Clause 2 also apply to CEN/TR 16797-1:2015. CEN/TR 16797-2:2015, Annex D contains a model clause and the rules of application introduced in this Part are drafted as normative text that may be copied into or cited by product standards. A recommended solution is to copy the

18、 model clause into the product standard and specify the rule of application given in CEN/TR 16797-2:2015, Annex D to be used. This Technical Report was developed on the basis of experience with the control of release into soil and water. As it is an assessment of data against a declared value regard

19、less of the source of the data, it is the technical view of CEN/TC 351 that these procedures are also valid for the assessment of emission from construction products into indoor air and assessment of gamma radiation from construction products. It is suggested that all product technical committees fo

20、llow the principles set out in this CEN Technical Report and it is hoped that all regulators will accept that these principles achieve their objectives with respect to an acceptable AVCP procedure. The rules of application are examples of the ways in which these principles may be applied. There is n

21、o obligation on a product technical committee to adopt these rules of application and they are free to determine their own rules of application. The given rules of application may also be used as a benchmark for assessing alternative rules of application. If product technical committees and producer

22、s could streamline their approaches in a way that could be accepted by all regulators, it might support a common understanding on the European market and it might encourage regulators to harmonize their existing different approaches and requirements on reliability and meaning of performance declarat

23、ions in legislation and enforcement. PD CEN/TR 16797-1:2015 CEN/TR 16797-1:2015 (E) 5 1 Scope This Technical Report provides guidance on the statistical assessment of declared values with respect to the release, emission and/or content of dangerous substances. This Technical Report provides statisti

24、cally-based criteria for type-testing (TT), further-testing (FT) and where a product has been shown to be consistent with measured values for the release, emission or content that are significantly below the declared values, the point where no-further-testing (NFT) is permitted. A series of fundamen

25、tal principles are defined in the present document and two statistical approaches are defined. The first approach is to use assessment by variables and this approach requires the data to be normally or log-normally distributed. This approach is recommended as the default option. The alternative appr

26、oach based on assessment by attributes is appropriate for data sets that are not normally or log-normally distributed. The downside to this form of assessment is that more test data are needed for the same level of reliability. The present document introduces these assessment procedures and CEN/TR 1

27、6797-2 provides more detail and the statistical proof that they satisfy the principles defined in this document. With both of these approaches the minimum frequency of testing is a function of the distance between the mean value and declared value and the variability of the data set, i.e. the sample

28、 standard deviation. To reduce the costs of testing, production plants producing a similar product may share data, e.g. be grouping the product into clusters for statistical assessment of declared values. Rules for the use of clusters are given in CEN/TR 16797-2. CEN/TR 16797-2 also contains rules f

29、or identifying outliers within a data set and guidance on using tests other than the reference method for FT. A list of tasks for product technical committees is given in CEN/TR 16797-2 as is a model clause for including in product standards and rules of applications that may be cited in the product

30、 standard or copied into product standards. 2 Declared values Any declared value with respect to the potential release, emission and/or content of dangerous substances needs to be justified. This justification is based on either: the product conforming to the conditions given in the relevant product

31、 standard for a declared value/class based on the without-further-testing concept; or, type-testing followed by further-testing at the determined frequency. Where there is no requirement to carry out a determination, the producer may declare performance for this characteristic as NPD using the no-pe

32、rformance determined option. The Construction Products Regulation 2 defines the ways in which a declaration of performance may be made by the producer. The declared value, or declared class, provides a level of release, emission and/or content that has a low probability of being exceeded in the prod

33、uction. A producer is free to select the value to be declared. The validity of the declared value is assessed using statistical techniques described in this CEN Technical Report using a sufficient number of tests according to a standardized test procedure (the reference test or a combination of test

34、s with the reference test and adequate indirect tests). The declared value applies on the scale of a batch as defined in the product standard. As it is a numerical value it can, where required, be compared directly with a limit value in a regulation or specification. If, in those cases, the declared

35、 value is equal to or less than the limit value, the product satisfies the requirement. A product technical committee is also free to introduce classes (as technical classes), but the upper numerical value defining these classes has the same technical meaning as a declared value. The lower numerical

36、 limit of the class will be zero. PD CEN/TR 16797-1:2015 CEN/TR 16797-1:2015 (E) 6 Where a product is to be placed on a regulated market, and where the mean value based on the reference test method is low in relation to the regulatory limit, a producer may benefit from setting the declared value at

37、the regulatory limit. Doing so will tend to minimize the test frequency and may lead to satisfying the conditions for no-further-testing (NFT) given in 5.2.6 and 5.4.6. Whereas, a declared value that is significantly lower than the regulatory limit, and hence much nearer to the mean value, will prob

38、ably result in a higher test frequency or even batch testing under these rules of application. On the other hand, setting a high declared value in order to minimize the test frequency might affect a products competitiveness in relation to products with a lower declared value. So the freedom for the

39、producer to select the declared value introduces more flexibility. It is, however, for the product technical committee to decide whether performance should be declared using declared values or classes or whether both options are permitted in its product standards. If the confidence at which the decl

40、ared value is to be achieved were only to be defined (qualitatively) as a low probability of being exceeded in the production, its meaning would be interpreted differently by different product technical committees and different regulators. In existing legislation and formal enforcement procedures in

41、 different Member States requirements are specified on the reliability of the declared values and while these specifications are not harmonized, the intentions are usually similar. Therefore, a common, agreed quantitative, i.e. statistical, definition is necessary and based on existing regulations a

42、nd experience, the following is proposed: Principle 1: The rules of application verify with a confidence of 90 % that the 50th percentile of the production is less than or equal to the declared value when the scale of declaration is a batch as defined in the product standard. Put another way, it sho

43、uld be expected that the average quality of a batch would be equal to or better than the declared value after taking into account uncertainty (see Clause 4). The criterion of 50th percentile may seem too relaxed, but in practice it means that products placed on the market will rarely exceed the decl

44、ared values. This is explained in detail in CEN/TR 16797-2. The rules of application described in this document all satisfy this principle and the technical explanation as to why is given in CEN/TR 16797-2:2015, Clause 8. In the following sections where the term declared value is used, it may be int

45、erchanged with the terms regulatory class limit or technical class limit. 3 Other principles It is assumed that the reader is familiar with the principles of the Construction Products Regulation and therefore these principles are not repeated in this Technical Report. There are also a number of prin

46、ciples associated with issues such as confidence in the test laboratory and rules for enforcement testing, but these are outside the scope of this Technical Report. The following principles all relate to the declared values with respect to the potential release, emission or content of dangerous subs

47、tances. Principle 2: The declared value relates to the performance of the product in a reference test procedure. The appropriate test method will be defined in the product standard. Principle 3: The test frequency is permitted to vary. The test frequency reduces as the risk of exceeding the declared

48、 value diminishes, e.g.: the distance between the mean value and the declared value increases; the standard deviation reduces. Producers should benefit from lower rates of testing where test results show low variability and where: declared values are particularly conservative i.e. where the mean val

49、ue is well below the declared value; PD CEN/TR 16797-1:2015 CEN/TR 16797-1:2015 (E) 7 and/or the mean value is well below a markets regulatory limit. This variable test frequency therefore acts as an incentive to producers to control their products and reduce the environmental impact. Principle 4: The production is split into batches in order to facilitate the variable test frequency. For continually produced products, the batch size associated with Principle 1 is not more than one tenth (10 %) of the production over one year and the max